Pulseox and transport

Q: People getting transported in an ambulance may have falsely ____________ pulse-oximetry (pulseox) level?

A) high

B) low

Answer: B

The objective of the question is to highlight the phenomenon of 'signal-to-noise ratio' in pulseox reading. Any motion or noise artifact tends to decrease the proper signally of pulse-ox and falsely lowers the pulseox reading. Following are a few common situations:

• shivering
• seizure activity
• pressure on the sensor
• transport (ambulance or helicopter)

It can be easily detected by an erratic and 'not normal' pulseox waveform. One of the remedies is to apply a newer pulseox probe, which may be less affected by noise or motion.

#oxygenation

References:

1. Grace RF. Pulse oximetry. Gold standard or false sense of security? Med J Aust 1994; 160:638.

2. Ortega R, Hansen CJ, Elterman K, Woo A. Videos in clinical medicine. Pulse oximetry. N Engl J Med 2011; 364:e33.

3. Barker SJ. "Motion-resistant" pulse oximetry: a comparison of new and old models. Anesth Analg 2002; 95:967.

4. Gehring H, Hornberger C, Matz H, et al. The effects of motion artifact and low perfusion on the performance of a new generation of pulse oximeters in volunteers undergoing hypoxemia. Respir Care 2002; 47:48.